This week, a report from Citigroup analyst Walter Pritchard said that royalty fee amounts to $5 per Android phone.

Late in 2010, HTC reportedly laid out a projection to ship 60 million Android smartphones in the calendar year of 2011; and with a $5 royalty fee, that would mean $300 million for Microsoft just from HTC this year. Pritchard says Microsoft is looking to establish similar deals with other Android phone makers through patent infringement lawsuits.

In late 2010, Microsoft announced that it had sued Motorola over its use of Android, and that Android infringed on nine of Microsoft's patents for "synchronizing email, calendars and contacts, scheduling meetings, and notifying applications of changes in signal strength and battery power." That case ended up before the International Trade Commission and Motorola filed a countersuit, accusing Microsoft's Xbox 360 and Kinect of three counts of patent infringement.

Pritchard's analysis cites 23 major lawsuits over Android and patent licensing between January 2010 and today.